Beef and Lamb New Zealand says updated figures of entrie farms being sold into forestry show New Zealand's current rate of afforestation is not sustainable.
The new land use report by Orme and Associates, commissioned by Beef and Lamb New Zealand, showed 261,000 hectares of sheep and beef farmland was converted into forestry between 2017 to the end of June this year.
These figures were revised following the industry group's last report in August last year to include farms converted to forestry after the sales were completed.
Most recently, 51,000 hectares of farmland tipped for afforestation were sold since the end of 2022.
Though, authors said the results for 2023 and the first two quarters of 2024 were still preliminary.
Beef and Lamb New Zealand chair, Kate Acland said the afforestation was being driven by Emissions Trading Scheme policy settings.
She said estimates that around one million sheep were lost for every 100,000 hectares of pine planted out showed how detrimental the situation was to rural and farming communities.
"There has already been a significant decline in stock numbers as a result of afforestation over the past few years," she said.
"There are a couple of years between when a farm is sold and trees go in the ground, so based on the high 2022 farm sales numbers we know there is still a lot more planting coming, and that will further impact stock numbers."
Sheep numbers fell 4.3 percent in the year to the end of June to 23.31 million, according to Beef and Lamb New Zealand's latest stock number survey in August.
Acland said it was concerned that whole farms on productive land were being sold for conversion to carbon farms.
"We're not saying there should be zero offsets available, we just want some limits around the conversion of whole farms into forestry for carbon credits," Acland said.
She said it supported whole-farm sale limits or a moratorium, while the Government worked out its policy settings around the Emissions Trading Scheme.
The Government has previously signalled it will announce policy direction to limit farm conversions to forestry on high-quality land to protect food production - which could include a moratorium on whole farm conversions.
"Any restrictions on forestry offsets should still allow farmers to enter some of their farm into the Emissions Trading Scheme regardless of land class," Acland said.
"Farmers should be able to plant trees on the parts of their farms where it's appropriate to plant, and to earn additional revenue from the ETS in the process."
However, the Forest Owners Association said despite the planting of carbon forests, New Zealand's total forestry remained 70,000 hectares less than it was 20 years ago.
Chief executive Elizabeth Heeg said farming and forestry co-existed with real benefits to the primary sector and to help meet climate targets.
"The reality is New Zealand needs a continued focus on the planting of carbon forests as we work towards meeting our climate change targets of 2050," she said.
"[The Association] supports landowners and farmers having the right to diversify their land through the planting of more trees."
Heeg said any suggested restriction of forest expansion would go against the rights of the farmer or landowner to make choices of how they want to use and diversify their land.
"Forestry can support those sheep and beef farmers who are wanting a more diversified portfolio, and many sheep and beef farmers are also foresters. The planting of more trees also improves environmental performance, provide timber and contributes to New Zealand's climate action," she said.
Report authors said there had been a change in where farmland was being sold for forestry since 2017 - with sales in the Gisborne region on the slowdown, while sales were up in Taranaki and Waikato since 2017.
Most sales took place in the North Island in that time.
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